libstdc++
atomic_2.h
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1 // -*- C++ -*- header.
2 
3 // Copyright (C) 2008, 2009
4 // Free Software Foundation, Inc.
5 //
6 // This file is part of the GNU ISO C++ Library. This library is free
7 // software; you can redistribute it and/or modify it under the
8 // terms of the GNU General Public License as published by the
9 // Free Software Foundation; either version 3, or (at your option)
10 // any later version.
11 
12 // This library is distributed in the hope that it will be useful,
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14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
16 
17 // Under Section 7 of GPL version 3, you are granted additional
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19 // 3.1, as published by the Free Software Foundation.
20 
21 // You should have received a copy of the GNU General Public License and
22 // a copy of the GCC Runtime Library Exception along with this program;
23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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25 
26 /** @file bits/atomic_2.h
27  * This is an internal header file, included by other library headers.
28  * You should not attempt to use it directly.
29  */
30 
31 #ifndef _GLIBCXX_ATOMIC_2_H
32 #define _GLIBCXX_ATOMIC_2_H 1
33 
34 #pragma GCC system_header
35 
36 // _GLIBCXX_BEGIN_NAMESPACE(std)
37 
38 // 2 == __atomic2 == Always lock-free
39 // Assumed:
40 // _GLIBCXX_ATOMIC_BUILTINS_1
41 // _GLIBCXX_ATOMIC_BUILTINS_2
42 // _GLIBCXX_ATOMIC_BUILTINS_4
43 // _GLIBCXX_ATOMIC_BUILTINS_8
44 namespace __atomic2
45 {
46  /// atomic_flag
47  struct atomic_flag : public __atomic_flag_base
48  {
49  atomic_flag() = default;
50  ~atomic_flag() = default;
51  atomic_flag(const atomic_flag&) = delete;
52  atomic_flag& operator=(const atomic_flag&) = delete;
53 
54  // Conversion to ATOMIC_FLAG_INIT.
55  atomic_flag(bool __i): __atomic_flag_base({ __i }) { }
56 
57  bool
58  test_and_set(memory_order __m = memory_order_seq_cst) volatile
59  {
60  // Redundant synchronize if built-in for lock is a full barrier.
61  if (__m != memory_order_acquire && __m != memory_order_acq_rel)
62  __sync_synchronize();
63  return __sync_lock_test_and_set(&_M_i, 1);
64  }
65 
66  void
67  clear(memory_order __m = memory_order_seq_cst) volatile
68  {
69  __glibcxx_assert(__m != memory_order_consume);
70  __glibcxx_assert(__m != memory_order_acquire);
71  __glibcxx_assert(__m != memory_order_acq_rel);
72 
73  __sync_lock_release(&_M_i);
74  if (__m != memory_order_acquire && __m != memory_order_acq_rel)
75  __sync_synchronize();
76  }
77  };
78 
79 
80  /// 29.4.2, address types
82  {
83  private:
84  void* _M_i;
85 
86  public:
87  atomic_address() = default;
88  ~atomic_address() = default;
89  atomic_address(const atomic_address&) = delete;
90  atomic_address& operator=(const atomic_address&) = delete;
91 
92  atomic_address(void* __v) { _M_i = __v; }
93 
94  bool
95  is_lock_free() const volatile
96  { return true; }
97 
98  void
99  store(void* __v, memory_order __m = memory_order_seq_cst) volatile
100  {
101  __glibcxx_assert(__m != memory_order_acquire);
102  __glibcxx_assert(__m != memory_order_acq_rel);
103  __glibcxx_assert(__m != memory_order_consume);
104 
105  if (__m == memory_order_relaxed)
106  _M_i = __v;
107  else
108  {
109  // write_mem_barrier();
110  _M_i = __v;
111  if (__m == memory_order_seq_cst)
112  __sync_synchronize();
113  }
114  }
115 
116  void*
117  load(memory_order __m = memory_order_seq_cst) const volatile
118  {
119  __glibcxx_assert(__m != memory_order_release);
120  __glibcxx_assert(__m != memory_order_acq_rel);
121 
122  __sync_synchronize();
123  void* __ret = _M_i;
124  __sync_synchronize();
125  return __ret;
126  }
127 
128  void*
129  exchange(void* __v, memory_order __m = memory_order_seq_cst) volatile
130  {
131  // XXX built-in assumes memory_order_acquire.
132  return __sync_lock_test_and_set(&_M_i, __v);
133  }
134 
135  bool
136  compare_exchange_weak(void*& __v1, void* __v2, memory_order __m1,
137  memory_order __m2) volatile
138  { return compare_exchange_strong(__v1, __v2, __m1, __m2); }
139 
140  bool
141  compare_exchange_weak(void*& __v1, void* __v2,
142  memory_order __m = memory_order_seq_cst) volatile
143  {
144  return compare_exchange_weak(__v1, __v2, __m,
145  __calculate_memory_order(__m));
146  }
147 
148  bool
149  compare_exchange_strong(void*& __v1, void* __v2, memory_order __m1,
150  memory_order __m2) volatile
151  {
152  __glibcxx_assert(__m2 != memory_order_release);
153  __glibcxx_assert(__m2 != memory_order_acq_rel);
154  __glibcxx_assert(__m2 <= __m1);
155 
156  void* __v1o = __v1;
157  void* __v1n = __sync_val_compare_and_swap(&_M_i, __v1o, __v2);
158 
159  // Assume extra stores (of same value) allowed in true case.
160  __v1 = __v1n;
161  return __v1o == __v1n;
162  }
163 
164  bool
165  compare_exchange_strong(void*& __v1, void* __v2,
166  memory_order __m = memory_order_seq_cst) volatile
167  {
168  return compare_exchange_strong(__v1, __v2, __m,
169  __calculate_memory_order(__m));
170  }
171 
172  void*
173  fetch_add(ptrdiff_t __d, memory_order __m = memory_order_seq_cst) volatile
174  { return __sync_fetch_and_add(&_M_i, __d); }
175 
176  void*
177  fetch_sub(ptrdiff_t __d, memory_order __m = memory_order_seq_cst) volatile
178  { return __sync_fetch_and_sub(&_M_i, __d); }
179 
180  operator void*() const volatile
181  { return load(); }
182 
183  void*
184  operator=(void* __v) // XXX volatile
185  {
186  store(__v);
187  return __v;
188  }
189 
190  void*
191  operator+=(ptrdiff_t __d) volatile
192  { return __sync_add_and_fetch(&_M_i, __d); }
193 
194  void*
195  operator-=(ptrdiff_t __d) volatile
196  { return __sync_sub_and_fetch(&_M_i, __d); }
197  };
198 
199  // 29.3.1 atomic integral types
200  // For each of the integral types, define atomic_[integral type] struct
201  //
202  // atomic_bool bool
203  // atomic_char char
204  // atomic_schar signed char
205  // atomic_uchar unsigned char
206  // atomic_short short
207  // atomic_ushort unsigned short
208  // atomic_int int
209  // atomic_uint unsigned int
210  // atomic_long long
211  // atomic_ulong unsigned long
212  // atomic_llong long long
213  // atomic_ullong unsigned long long
214  // atomic_char16_t char16_t
215  // atomic_char32_t char32_t
216  // atomic_wchar_t wchar_t
217 
218  // Base type.
219  // NB: Assuming _ITp is an integral scalar type that is 1, 2, 4, or 8 bytes,
220  // since that is what GCC built-in functions for atomic memory access work on.
221  template<typename _ITp>
222  struct __atomic_base
223  {
224  private:
225  typedef _ITp __integral_type;
226 
227  __integral_type _M_i;
228 
229  public:
230  __atomic_base() = default;
231  ~__atomic_base() = default;
232  __atomic_base(const __atomic_base&) = delete;
233  __atomic_base& operator=(const __atomic_base&) = delete;
234 
235  // Requires __integral_type convertible to _M_base._M_i.
236  __atomic_base(__integral_type __i) { _M_i = __i; }
237 
238  operator __integral_type() const volatile
239  { return load(); }
240 
241  __integral_type
242  operator=(__integral_type __i) // XXX volatile
243  {
244  store(__i);
245  return __i;
246  }
247 
248  __integral_type
249  operator++(int) volatile
250  { return fetch_add(1); }
251 
252  __integral_type
253  operator--(int) volatile
254  { return fetch_sub(1); }
255 
256  __integral_type
257  operator++() volatile
258  { return __sync_add_and_fetch(&_M_i, 1); }
259 
260  __integral_type
261  operator--() volatile
262  { return __sync_sub_and_fetch(&_M_i, 1); }
263 
264  __integral_type
265  operator+=(__integral_type __i) volatile
266  { return __sync_add_and_fetch(&_M_i, __i); }
267 
268  __integral_type
269  operator-=(__integral_type __i) volatile
270  { return __sync_sub_and_fetch(&_M_i, __i); }
271 
272  __integral_type
273  operator&=(__integral_type __i) volatile
274  { return __sync_and_and_fetch(&_M_i, __i); }
275 
276  __integral_type
277  operator|=(__integral_type __i) volatile
278  { return __sync_or_and_fetch(&_M_i, __i); }
279 
280  __integral_type
281  operator^=(__integral_type __i) volatile
282  { return __sync_xor_and_fetch(&_M_i, __i); }
283 
284  bool
285  is_lock_free() const volatile
286  { return true; }
287 
288  void
289  store(__integral_type __i,
290  memory_order __m = memory_order_seq_cst) volatile
291  {
292  __glibcxx_assert(__m != memory_order_acquire);
293  __glibcxx_assert(__m != memory_order_acq_rel);
294  __glibcxx_assert(__m != memory_order_consume);
295 
296  if (__m == memory_order_relaxed)
297  _M_i = __i;
298  else
299  {
300  // write_mem_barrier();
301  _M_i = __i;
302  if (__m == memory_order_seq_cst)
303  __sync_synchronize();
304  }
305  }
306 
307  __integral_type
308  load(memory_order __m = memory_order_seq_cst) const volatile
309  {
310  __glibcxx_assert(__m != memory_order_release);
311  __glibcxx_assert(__m != memory_order_acq_rel);
312 
313  __sync_synchronize();
314  __integral_type __ret = _M_i;
315  __sync_synchronize();
316  return __ret;
317  }
318 
319  __integral_type
320  exchange(__integral_type __i,
321  memory_order __m = memory_order_seq_cst) volatile
322  {
323  // XXX built-in assumes memory_order_acquire.
324  return __sync_lock_test_and_set(&_M_i, __i);
325  }
326 
327  bool
328  compare_exchange_weak(__integral_type& __i1, __integral_type __i2,
329  memory_order __m1, memory_order __m2) volatile
330  { return compare_exchange_strong(__i1, __i2, __m1, __m2); }
331 
332  bool
333  compare_exchange_weak(__integral_type& __i1, __integral_type __i2,
334  memory_order __m = memory_order_seq_cst) volatile
335  {
336  return compare_exchange_weak(__i1, __i2, __m,
337  __calculate_memory_order(__m));
338  }
339 
340  bool
341  compare_exchange_strong(__integral_type& __i1, __integral_type __i2,
342  memory_order __m1, memory_order __m2) volatile
343  {
344  __glibcxx_assert(__m2 != memory_order_release);
345  __glibcxx_assert(__m2 != memory_order_acq_rel);
346  __glibcxx_assert(__m2 <= __m1);
347 
348  __integral_type __i1o = __i1;
349  __integral_type __i1n = __sync_val_compare_and_swap(&_M_i, __i1o, __i2);
350 
351  // Assume extra stores (of same value) allowed in true case.
352  __i1 = __i1n;
353  return __i1o == __i1n;
354  }
355 
356  bool
357  compare_exchange_strong(__integral_type& __i1, __integral_type __i2,
358  memory_order __m = memory_order_seq_cst) volatile
359  {
360  return compare_exchange_strong(__i1, __i2, __m,
361  __calculate_memory_order(__m));
362  }
363 
364  __integral_type
365  fetch_add(__integral_type __i,
366  memory_order __m = memory_order_seq_cst) volatile
367  { return __sync_fetch_and_add(&_M_i, __i); }
368 
369  __integral_type
370  fetch_sub(__integral_type __i,
371  memory_order __m = memory_order_seq_cst) volatile
372  { return __sync_fetch_and_sub(&_M_i, __i); }
373 
374  __integral_type
375  fetch_and(__integral_type __i,
376  memory_order __m = memory_order_seq_cst) volatile
377  { return __sync_fetch_and_and(&_M_i, __i); }
378 
379  __integral_type
380  fetch_or(__integral_type __i,
381  memory_order __m = memory_order_seq_cst) volatile
382  { return __sync_fetch_and_or(&_M_i, __i); }
383 
384  __integral_type
385  fetch_xor(__integral_type __i,
386  memory_order __m = memory_order_seq_cst) volatile
387  { return __sync_fetch_and_xor(&_M_i, __i); }
388  };
389 
390 
391  /// atomic_bool
392  // NB: No operators or fetch-operations for this type.
393  struct atomic_bool
394  {
395  private:
396  __atomic_base<bool> _M_base;
397 
398  public:
399  atomic_bool() = default;
400  ~atomic_bool() = default;
401  atomic_bool(const atomic_bool&) = delete;
402  atomic_bool& operator=(const atomic_bool&) = delete;
403 
404  atomic_bool(bool __i) : _M_base(__i) { }
405 
406  bool
407  operator=(bool __i) // XXX volatile
408  { return _M_base.operator=(__i); }
409 
410  operator bool() const volatile
411  { return _M_base.load(); }
412 
413  bool
414  is_lock_free() const volatile
415  { return _M_base.is_lock_free(); }
416 
417  void
418  store(bool __i, memory_order __m = memory_order_seq_cst) volatile
419  { _M_base.store(__i, __m); }
420 
421  bool
422  load(memory_order __m = memory_order_seq_cst) const volatile
423  { return _M_base.load(__m); }
424 
425  bool
426  exchange(bool __i, memory_order __m = memory_order_seq_cst) volatile
427  { return _M_base.exchange(__i, __m); }
428 
429  bool
430  compare_exchange_weak(bool& __i1, bool __i2, memory_order __m1,
431  memory_order __m2) volatile
432  { return _M_base.compare_exchange_weak(__i1, __i2, __m1, __m2); }
433 
434  bool
435  compare_exchange_weak(bool& __i1, bool __i2,
436  memory_order __m = memory_order_seq_cst) volatile
437  { return _M_base.compare_exchange_weak(__i1, __i2, __m); }
438 
439  bool
440  compare_exchange_strong(bool& __i1, bool __i2, memory_order __m1,
441  memory_order __m2) volatile
442  { return _M_base.compare_exchange_strong(__i1, __i2, __m1, __m2); }
443 
444 
445  bool
446  compare_exchange_strong(bool& __i1, bool __i2,
447  memory_order __m = memory_order_seq_cst) volatile
448  { return _M_base.compare_exchange_strong(__i1, __i2, __m); }
449  };
450 } // namespace __atomic2
451 
452 // _GLIBCXX_END_NAMESPACE
453 
454 #endif
atomic_flag
Definition: atomic_2.h:47
memory_order
Enumeration for memory_order.
Definition: stdatomic.h:47
atomic_bool
Definition: atomic_2.h:393
29.4.2, address types
Definition: atomic_2.h:81